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What is binascii.a2b_base64 in Python?

Samia Ishaque

Overview

The binascii module in Python contains many functions that help convert data between binary and ASCII representations. binascii is necessary because the conversion of big data is slow in Python.

The function .a2b_base64 converts data of type base64 to binary and returns bytes.

What is base64 data?

base64 data is a way of representing data as shown in the table below:

Base64 Representation

Value

Encoding

Value

Encoding

Value

Encoding

Value

Encoding

0

A

17

R

34

i

51

z

1

B

18

S

35

j

52

0

2

C

19

T

36

k

53

1

3

D

20

U

37

l

54

2

4

E

21

V

38

m

55

3

5

F

22

W

39

n

56

4

6

G

23

X

40

o

57

5

7

H

24

Y

41

p

58

6

8

I

25

Z

42

q

59

7

9

J

26

a

43

r

60

8

10

K

27

b

44

s

61

9

11

L

28

c

45

t

62

+

12

M

29

d

46

u

63

/

13

N

30

e

47

v



14

O

31

f

48

w



15

P

32

g

49

x



16

Q

33

h

50

y



When a string is converted to base64 data type, each character of the string is mapped to a number in base64, which is then represented as an 8-bit binary number.

base64 data is commonly used in mail servers, as it decreases the likelihood of data becoming corrupted during transmission; this is because base64 data type allows us to convert both binary or text data type into ASCII characters.

Example

In the code below, we import the binascii and base64 modules. First, we convert our string data to ASCII using the encode() method. The returned data is input into base64.b64encode() to convert our string completely into base64 data type. Once the string has been converted, it can be input into binascii.a2b_base64() to convert to bytes.

The binascii.a2b_base64() method is used in cryptography to generate keys and authenticate credentials.

import binascii
import base64

message = "Hello World!"
encode_string = message.encode('ascii')
b64_string = base64.b64encode(encode_string)

string = binascii.a2b_base64(b64_string)
print(string)

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